Wireless charging or powering of devices in general is an established technique that is convenient to users. Wireless powering can also be used in harsh environments where corrosion or moisture might jeopardize functionality or safety when galvanic contacts are used. There are several standards for wireless power such as Qi, PMA, Rezense and WiPower, and the market is growing rapidly. These techniques are mostly used for charging a battery powered device (e.g. a mobile phone, a tablet computer, etc.). Charging of multiple devices is possible. For instance in the Qi standard power plates with many smaller coils are available, however the devices need to be precisely positioned adjacent to each other (in the horizontal plane).
High-end patient monitoring is expanding from its traditional application in the critical care arena (ICU, OR) towards lower acuity settings such as the general ward, hospital-to-home, connected primary care, etc. The success of the existing high-end products is due to the quality of the measurements, their modularity, the overall system connectivity, the user interface and its consistency (backwards compatibility) across the total product line. At the same time the value segment market is expanding rapidly to address emerging countries and lower acuity settings where low-cost is of prime concern. In these markets compromises may be made on modularity, connectivity and (sometimes) measurement quality.
In the lifestyle and sports arena also physiological measurements are used more and more (such as heart rate, respiration rate, SpO2).
In said new application spaces wearable (cordless) sensors, miniaturization and low-power are necessary. The basic requirements across all these segments are the same, namely excellent measurement quality compared with non-compromised electrical patient safety. The latter is strictly regulated in the IEC 60601 standard and dictates in a worst case scenario (direct connection to the heart) a 10 μA maximum leakage current, 4 kV isolation towards ground and 1.5 kV isolation between each of the measurements. Additionally, the patient monitor must be able to withstand high differential voltages introduced by a defibrillator and large RF voltages from a surgical knife.
Conventional isolation and protection concepts are based on inductive power couplers (transformers) and optical data couplers for data transport, next to maintaining sufficient creeping and clearance between PCBs and connector pins.
U.S. Pat. No. 6,819,013 B2 discloses an electrically isolated, combined power and signal coupler for a patient connected device. A docking station and a portable device, capable of docking with the docking station each include a power coupler and an electrically isolated data transducer. The respective power couplers include a magnetically permeable element including a central pole and a peripheral pole and a printed circuit board with an opening through which the central pole protrudes. The printed circuit board includes windings surrounding the central pole opening including a primary winding in the docking station and a secondary winding in the portable device. When the portable device is docked with the docking station, the magnetically permeable element in the portable device and the magnetically permeable element in the docking station are arranged to form a magnetic circuit, and the data transducer in the portable device and the data transducer in the docking station are arranged to exchange data.
US 2013/046197 A1 discloses a docking apparatus comprising a processor, a battery charging module, a storage device, and one or more ports, which are configured to couple with patient monitoring units. Each patient monitoring unit is operable to monitor at least one physiological parameter of a patient. The battery charging module charges the patient monitoring units through the ports. The storage device stores data received from the patient monitoring units through the ports. The processor transmits updates to the patient monitoring units through the ports. The ports may comprise sockets that receive plugs from cables of the patient monitoring units. The docking apparatus may comprise a plurality of separate dock housings associated with corresponding patient monitoring units. These dock housings being joined together in a daisy chain. The docking apparatus may also include a plurality of docking recesses in a single housing, with each docking recess being associated with a corresponding patient monitoring unit.
Mark Cantrell: “Digital Isolator Simplifies USB Isolation in Medical and Industrial Applications”, Analog Dialogue 43-06, June (2009), XP055052417, www.analog.com/analogdialogue, discloses various ways of applying isolation with USB, e.g. an isolated cable interface including a a chip-scale device that supports direct isolation of low- and full-speed USB D+ and D− lines.